The 46-year-old actor, who appeared on "The Tonight Show Starring Jimmy Fallon", was seen making hand gestures as the host took a commercial break.
One of the activists Nyle DiMarco took to Twitter where he posted a statement calling out Foxx's behaviour and said what the "Django Unchained" star did "should not be tolerated anywhere".
"We simply do not make fun at the expense of other cultures, especially those with a history of being marginalised.
"What Foxx did on 'Fallon Tonight' made our struggle much harder," he wrote.
Matlin, who won the Academy Award for "Children of a Lesser God" (1987), is the only deaf artiste to have won the award.